More than 50 people, including three US citizens and a Belgian, have gone on trial in the Democratic Republic of Congo over what the army has described as an attempted coup. The actions of the three Americans were “punishable by death”, Judge Freddy Ehume told the military court in the DRC capital, Kinshasa. Marcel Malanga and Taylor Christian Thomson, both 21, and 36-year-old Benjamin Reuben Zalman-Polun were the first of the defendants to stand before the judge to hear the charges read out against them. “These acts are punishable by death,” the presiding judge of the Kinshasa-Gombe military court told the three. Another 50 or so defendants then took the stand one by one under a large tent in the grounds of the Ndolo military prison to hear the charges. All appeared in blue-and-yellow prison uniforms at their trial, which started at about 11.40am local time and was followed closely by western diplomats, journalists and lawyers. The alleged coup attempt occurred on 19 May, when armed men attacked the home of the economy minister, Vital Kamerhe, in the early hours before moving on to the nearby Palais de la Nation that houses President Felix Tshisekedi’s offices. They were seemingly filmed brandishing the flag of Zaire – the name of the central African country during the rule of the dictator Mobutu Sese Seko – and chanting that Tshisekedi’s government was over. The army later announced on national television that security forces had stopped “an attempted coup d’état”. The alleged plot was led by Christian Malanga, a Congolese man who was a “naturalised American” and who was killed by security forces, the army spokesperson Gen Sylvain Ekenge said. Malanga’s son, who is a US citizen, was one of the three Americans to face trial on Friday. Ekenge said about 40 of the assailants, of “various nationalities”, had been arrested and a further four killed, including Christian Malanga. The motive behind the alleged incident remains unclear but the government condemned it as an attempt to “destabilise” the vast country’s “institutions”. Four women are among the accused, as well as at least one Belgian national, Jean-Jacques Wondo. Wondo, a military expert of Congolese origin, was arrested two days after the events, on 21 May. He is accused of being an “accomplice of Christian Malanga” by “providing transport” for the alleged putschists, his lawyer, Masingo Shela, said. Wondo denied the charge against him and would defend himself, Shela added. According to a court document, a total of 53 defendants are being tried, including Christian Malanga, even though he is dead. The charges include “attack, terrorism, illegal possession of weapons and munitions of war, attempted assassination, criminal association, murder [and] financing of terrorism”, according to the document.